Ignition cable having predetermined resistance

ABSTRACT

Ignition cable for spark ignition engine comprises an insulated cable with a metallic conducting core. A large diameter hole extends transversely through the cable adjacent to one end and a resistor is positioned in this hole. One lead from the resistor extends from the hole rearwardly along the surface of the cable, thence radially into the cable and contacts the core. The other lead extends from the hole towards the end of the cable. A terminal crimped onto the end of the cable is in electrical contact with the other lead so that the resistor is in series with the conducting core of the cable.

[ Apr. 2, 1974 United States Patent 1 1 Wise [5 IGNITION CABLE HAVING Primary ExaminerE. A. Goldberg PREDETERMINED RESISTANCE Attorney, Agent, or Firm-William J. Keating [75] Inventor: Joseph Agusta Wise, Hershey, Pa. [73] Assignee: AMP Incorporated, Harrisburg, Pa.

[22 Filed:

ABSTRACT Ignition cable for spark ignition engine comprises an 27 June 1973 insulated cable with a metallic conducting core. A large diameter hole extends transversely through the [2]] Appl. No.: 374,158

' cable adjacent to one end and a resistor is positioned in this hole. One lead from the resistor extends from the hole rearwardly along the surface of the cable,

[51] Int. H016 1/06 338/66, 211, 322

thence radially into the cable and contacts the core.

[58] Field of The other lead extends from the hole towards the end of the cable. A terminal crimped onto the end of the cable is in electrical contact with the other lead so that the resistor is in series with the conducting core of the cable.

References Cited UNITED STATES PATENTS 3,212,044 Cloud 3,315,206 4/1967 Dresser 6 Claims, 4 Drawing Figures BACKGROUND OF THE INVENTION It is common practice to use graphite conductors for the insulated cables which extend from the distributor of a spark ignition engine to the spark plugs of the engine and from the ignition coil to the distributor. Such graphite conductor cables are used because of the fact that they have a high resistance which is desirable in ignition cables in order to suppress radio frequency interference caused by the ignition system. A graphite type ignition cable can be produced at low cost and is satisfactory for many purposes and under many circumstances.

It is desirable however, to use a conventional metallic conductor cable under some circumstances. Graphite cables are subject to deterioration with time and a failure in'the ignition system can result/Furthermore, the

total resistances of a graphite ignition cable is directly proportional to its length and different cables can therefore, have widely varying resistances. A cable having a metallic conductorwith a resistor in series with the conductor'would not have these disadvantages but previously proposed metallic ignition cables have not been economically feasible.

It is accordingly an object of the invention to provide an improved ignition cable. A further object is to provide a metallic conductor ignition cable having a predetermined electrical resistance. A further object is to provide an ignition cable having a metallic conductor and a resistor in series with the cable conductor which is economical to manufacture, reliable, and predictable as to its electrical characteristics.

These and other objects of the invention are achieved in preferred embodiments thereof which are briefly described in the foregoing abstract, which are described in the detail below and which are shown .in the accompanying drawing in which:

FIG. 1 is a perspective view of a section of an electricalcable having holes punched therein in accordance with a preferred method of manufacturing cables in accordance with the invention.

- FIG. 2 is a view similar to FIGII but showing an electrical resistor positioned in the cable, this view illustrating a further manufacturing strip.

FIG. 3 is a side view of an ignition cable in accordance with the invention.

FIG. 4 illustrates the use of an ignition cable in accordance with the invention.

The embodiment of the invention shown in the drawing can best be described by describing the manner in which it is manufactured. An ignition cable in accordance with the invention is preferably manufactured from a cable 2 having a central metallic conducting core 4 and an insulating sheath 6 in surrounding relationship to the core. The metallic conductor 4 is preferably copper clad steel or tin coated steel, for example, AWG 20 wire having 7 strands. The insulating sheath 6 may be any suitable plastic or rubber-like material but is preferably relatively thick asshown.

In the manufacture of the ignition cable assembly, a first hole 8 is formed in the cable adjacent to one end 10 thereof. This hole may be formed by punching and 7 should be of a diameter such that a portion of a core 4 is removed so that the end portion 9 of the metallic core is electrically separated from the remainder of the core. A second hole 12 is formed in the cable which is relatively remote from the end 10 but adjacent to the hole 8. This hole 12 may be formed with any suitable small punch or with a pointed piercing tool of a smalldiameter. In any event, the conducting core 4 should not be severed and preferably none of the strands should be cut.

A resistor 14 of suitable value for example, 5,600 ohms, is then positioned in the hole 8 and one lead 16 v of this resistor is bent rightwardly in FIG. 2 and inserted through the hole 12 so that this lead electrically contacts the conductor 4 as indicated at 18. It has been found that adequate electrical contact is obtained if the lead 16 is simply pushed between the strands of the conductor 4 although the lead 16 can be soldered to the strands.

The other lead 20, of the resistor 14 extends from the other end of the hole 8 and is bent so that it is against the insulation of the end portion 26 of the cable as shown in FIG. 2. An electrical terminal 22 is then crimped onto the end of the cable as shown in FIG. 3. This cable has a cylindrical crimped portion 24 which surrounds the end of the cable in fairly tight relationship so that the end of the lead 20 will be held by the compressed insulation against the internal surface of crimped portion 24. The terminal 22 also has a laterally extending receptacle portion 28 which is adapted to receive a complementary terminal 30 on a spark plug 32.

It will be apparent from the foregoing that the electrical path from the distributor 34 to the spark plug 32 extends through and along the conductor 4 to the lead 16 thence through the resistor 14 and through the lead 20 to the terminal 22 and to the spark plug. The resistor is thus in series with the conductor 4. As previously noted, the hole 8 should be of a diameter such that a portion of the conductor 4 is removed so that the end section 9 of the conductor is electrically isolated and carries no current. If the precaution is taken of forming the hole of such a diameter, the resistor will not be short circuited if the exposed end of the portion 9 of the conductor should come into contact with the terminal'22.

It is common practice to provide a terminal 36 on the end of an iginition cable which is plugged into the distributor 34 of the ignition system. It will be apparent that a resistor can be mounted in the cable adjacent to the terminal 36 rather than the terminal 22 and connected in series to the conductor 4 in accordance with the teachings of the FIGS. 1-3.

It will be apparent from the foregoing that a resistance cable in accordance with the invention can be easily manufactured and that any suitable terminal 24 can be used, for example, terminals of the type presently being used for graphite conductor cables. By virtue of the fact that most of the resistance of the cable is in the resistor 14 rather than in the conducting material of the cable, a set of cablesfor an engine will all have the same resistance rather than a resistance which will depend upon a length of the cable as is the case with graphite conductor cable. Furthermore, the characteristics of a cable in accordance with the invention are predictable and predetermined with a high degree of precision and cables in accordance with the invention are highly resistent to deterioration resulting from the decomposition or physical deterioration of the conductor 4. A metallic conductor is virtually immune to deterioration under even the most adverse circumthe distributor of the engine to a spark plug. it will be understood that the cable 38 which extends from the coil 40 to the distributor must also have a relatively high resistance and the principles of the invention can be employed in the high resistance cable which extends between the coil and the distributor.

Changes in construction will occur to those skilled in the art and various apparently different modifications and embodiments may be made without departing from the scope of the invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only.

What is claimed is: g

1. Ignition cable means for a spark-ignition engine comprising:

I an elongated cable comprising a single metallic conductor and an insulating sheath in surrounding relation-ship to said metallic conductor,

an opening extending transversely through said cable adjacent to one end thereof,

an electrical resistor, said resistor having two leads extending therefrom,

one of said leads extending through said hole and being in electrical contact with said conductor,

portions of the other one of said leads extending along said sheath between said hole and said one end of said cable,

a terminal having a-ferrule portion crimped onto said cable adjacent to said one end, said ferrule portion being in surrounding relationship to said sheath and being in electrical contact with said portions of I said other one of said leads, and

connecting means on said terminal for forming an electrical connection to the ignition system of an engine.

2. Cable means as set forth in claim 1, said connecting means comprising means for forming an electrica connection to a spark plug. 1 3. Cable means as set forth in claim 1, said connecting means comprising means for forming an electrical connection to a distributor.

4. Cable means as set forth in claim 1, said connecting means comprising means for forming an electrical connection to the coil of an ignition system.

5. Cable means as set forth in claim 1, said cable having an additional hole extending therethrough, said additional hole being between said hole and said one end of said cable, said resistor being in said additional hole.

6. Ignition cable means for a spark-ignition engine comprising: I v

an elongated cable comprising a single central metallic conductor and an insulating sheath in surrounding relationship to said conductor,

first and second holes extending transversely through said cable, said first hole being relatively proximate to one end of said cable and having a diameter which is greater than the diameter of said metallic conductor whereby said conductor is fully electrically interrupted,

said second hole being adjacent to said first holeand relatively remote from said one end,

an electrical resistor in said first hole, said resistor having two leads extending therefrom,

one of said leads extending from said first hole thence along said cable to said second hole and into said second hole and said one lead being in electrical contact with said conductor,

the other one of said leads extending from said first hole and along said sheath towards said one end of said cable and an electrical terminal crimped onto said sheath at said one end, said terminal being in electrical contact with said other lead and not with said one lead. 

1. Ignition cable means for a spark-ignition engine comprising: an elongated cable comprising a single metallic conductor and an insulating sheath in surrounding relation-ship to said metallic conductor, an opening extending transversely through said cable adjacent to one end thereof, an electrical resistor, said resistor having two leads extending therefrom, one of said leads extending through said hole and being in electrical contact with said conductor, portions of the other one of said leads extending along said sheath between said hole and said one end of said cable, a terminal having a ferrule portion crimped onto said cable adjacent to said one end, said ferrule portion being in surrounding relationship to said sheath and being in electrical contact with said portions of said other one of said leads, and connecting means on said terminal for forming an electrical connection to the ignition system of an engine.
 2. Cable means as set forth in claim 1, said connecting means comprising means for forming an electrical connection to a spark plug.
 3. Cable means as set forth in claim 1, said connecting means comprising means for forming an electrical connection to a distributor.
 4. Cable means as set forth in claim 1, said connecting means comprising means for forming an electrical connection to the coil of an ignition system.
 5. Cable means as set forth in claim 1, said cable having an additional hole extending therethrough, said additional hole being between said hole and said one end of said cable, said resistor being in said additional hole.
 6. Ignition cable means for a spark-ignition engine comprising: an elongated cable comprising a single central metallic conductor and an insulating sheath in surrounding relationship to said conductor, first and second holes extending transversely through said cable, said first hole being relatively proximate to one end of said cable and having a diameter which is greater than the diameter of said metallic conductor whereby said conductor is fully electrically interrupted, said second hole being adjacent to said first hole and relatively remote from said one end, an electrical resistor in said first hole, said resistor having two leads extending therefrom, one of said leads extending from said first hole thence along said cable to said second hole and into said second hole and said one lead being in electrical contact with said conductor, the other one of said leads extending from said first hole and along said sheath towards said one end of said cable and an electrical terminal crimped onto said sheath at said one end, said terminal being in electrical contact with said other lead and not with said one lead. 